A Programmably Compliant Origami Mechanism for Dynamically Dexterous Robots

We present an approach to overcoming challenges in dynamical dexterity for robots through programmably compliant origami mechanisms. Our work leverages a one-parameter family of flat sheet crease patterns that folds into origami bellows, whose axial compliance can be tuned to select desired stiffness. Concentrically arranged cylinder pairs reliably manifest additive stiffness, extending the programmable range by nearly an order of magnitude and achieving bulk axial stiffness spanning 200–1500 N/m using 8 mil thick polyester-coated paper. Accordingly, we design origami energy-storing springs with a stiffness of 1035 N/m each and incorporate them into a three degree-of-freedom (DOF) tendon-driven spatial pointing mechanism that exhibits trajectory tracking accuracy less than 15% rms error within a (2 cm)^3 volume. The origami springs can sustain high power throughput, enabling the robot to achieve asymptotically stable juggling for both highly elastic (1 kg resilient shotput ball) and highly damped (“medicine ball”) collisions in the vertical direction with apex heights approaching 10 cm. The results demonstrate that “soft” robotic mechanisms are able to perform a controlled, dynamically actuated task

Turbulence induced beam spreading of higher order mode optical waves

It is well known that laser beams spread as they propagate through free space due to natural diffraction, and that there is additional spreading when optical waves propagate through atmospheric turbulence. Previous studies on Gaussian beams have mainly involved the lowest order mode (zero order). The study of higher order mode Gaussian beams has involved Hermite-Gaussian and Laguerre-Gaussian beams for rectangular and cylindrical geometry, respectively, These studies have developed expressions for the field and intensity in free space, in addition to developing new definitions of beam size in the receiver plane for the higher order modes. We calculate the mean intensity of higher order mode Gaussian beams propagating through atmospheric turbulence, and, based on previously developed definitions for beam radius, we calculate the additional beam spreading due to random media. It is shown that higher order mode Gaussian beams experience less percentage of additional broadening due to atmospheric fluctuations than the zero-order mode beams

Atomic scale coexistence of periodic and quasiperiodic order in a 2-fold Al-Ni-Co decagonal quasicrystal surface

Decagonal quasicrystals are made of pairs of atomic planes with pentagonal symmetry periodically stacked along a 10-fold axis. We have investigated the atomic structure of the 2-fold surface of a decagonal Al-Ni-Co quasicrystal using scanning tunneling microscopy. The surface consists of terraces separated by steps of heights 1.9, 4.7, 7.8, and 12.6 Å containing rows of atoms parallel to the 10-fold direction with an internal periodicity of 4 Å. The rows are arranged aperiodically, with separations that follow a Fibonacci sequence and inflation symmetry. The results indicate that the surfaces are preferentially Al-terminated and in general agreement with bulk models

Tribological properties of quasicrystals: Effect of aperiodic versus periodic surface order

We investigated the nanoscale tribological properties of a decagonal quasicrystal using a combination of atomic force microscopy and scanning tunneling microscopy in ultrahigh vacuum. This combination permitted a variety of in situ measurements, including atomic-scale structure, friction and adhesion force, tip-sample current, and topography. We found that thiol-passivated tips can be used for reproducible studies of the tip-quasicrystal contact while nonpassivated probes adhere irreversibly to the clean quasicrystalline surface causing permanent modifications. The most remarkable results were obtained on the twofold surface of the Al-Ni-Co decagonal quasicrystal where atoms are arranged periodically along the tenfold axis and aperiodically in the perpendicular direction. Strong friction anisotropy was observed on this surface, with high friction along the periodic direction and low friction in the aperiodic direction

Elastic and inelastic deformations of ethylene-passivated tenfold decagonal Al-Ni-Co quasicrystal surfaces

The adhesion and friction force properties between a tenfold Al‐Ni‐Co decagonal quasicrystal and a titanium nitride (TiN)-coated tip were investigated using an atomic force microscope in ultrahigh vacuum. To suppress the strong chemical adhesion found in the clean quasicrystal surfaces, the sample was exposed to ethylene that formed a protective passivating layer. We show that the deformation mechanism of the tip-substrate junction changes from elastic to inelastic at a threshold pressure of 3.8 to 4.0 GPa. Images of the indentation marks left above the threshold pressure indicate the absence of new steps, and indicate that surface damage is not accompanied by formation of slippage planes or dislocations, as found in plastically deforming crystalline materials. This is consistent with the lack of translational periodicity of quasicrystals. The work of adhesion in the inelastic regime is five times larger than in the elastic one, plausibly as a result of the displacement of the passivating layer. In the elastic regime, the friction dependence on load is accurately described by the Derjaguin-Müller-Toporov (DMT) model, consistent with the high hardness of both the TiN tip and the quasicrystal sample. Above the threshold pressure, the friction versus load curve deviates from the DMT model, indicating that chemical bond formation and rupture contribute to the energy dissipation

Unknown Rectal Lesions: A Case of Severe Proctitis Secondary to Mpox in the Setting of Concomitant HIV, Syphilis, HSV, and Chlamydia

Introduction: Mpox emerged as a public health crisis with limited research describing co-occurring HIV and sexually transmitted infections (STIs). We present a case of severe proctitis secondary to Mpox with concomitant HIV (Human Immunodeficiency Virus), syphilis, HSV (Herpes Simplex Virus), and chlamydia and review presentation, diagnosis, treatment, and prevention of Mpox with concurrent STIs. Case Presentation: 34-year-old male living with HIV (LWH) presenting with worsening rectal pain, multiple anal papules, and fever. His laboratory workup revealed simultaneous positive results for orthopoxvirus, chlamydia, and HSV-1 PCR. We initiated tecovirimat due to rectal involvement and uncontrolled pain. He subsequently developed lesions on hands as rectal pain improved. He completed tecovirimat treatment and the lesions cleared by outpatient follow-up. Discussion: Among published studies of Mpox patients, 40% were LWH, and a significant percent were found to have co-occurring gonorrhea (23%), chlamydia (20%), syphilis (8%), and HSV (1%) with presentations including fever (62%), lymphadenopathy (49%), malaise (39%), and rectal pain (25%). We recommend Mpox and full STI diagnostic testing for unknown anogenital lesions and early treatment should be considered. Early initiation of Tecovirimat treatment should be considered in severe disease, immune deficiency, or those at high-risk for serious sequelae, in accordance with CDC guidelines. Learning Points: Identify the differential diagnosis for unknown rectal lesions Describe the clinical presentation of Mpox Summarize the diagnostic approach and interpretation of diagnostic results Identify treatment options and considerations by patient populations Review preventative strategies and high-risk populations for Mpox transmissio

Sensing Dipole Fields at Atomic Steps with Combined Scanning Tunneling and Force Microscopy

The electric field of dipoles localized at the atomic steps of metal surfaces due to the Smoluchowski effect were measured from the electrostatic force exerted on the biased tip of a scanning tunneling microscope. By varying the tip-sample bias the contribution of the step dipole was separated from changes in the force due to van der Waals and polarization forces. Combined with electrostatic calculations, the method was used to determine the local dipole moment in steps of different heights on Au(111) and on the twofold surface of an Al-Ni-Co decagonal quasicrystal

Hubungan Kandidiasis Intertriginosa dan Diabetes Melitus Tipe 2 di Poliklinik Kulit dan Kelamin RSUD Dokter Soedarso Pontianak pada Tahun 2012

Background. Intertriginous candidiasis is a type of cutaneous candidiasiswhich is located at the axila, inguinal, intergluteal, inframammary,interdigitalis, glands penis, and umbilicus. One of the risk factors ofintertriginous candidiasis patient is people with diabetes mellitus (DM).The increase of glucose concentration makes more susceptible frominfection. Objective. Define the association between intertriginouscandidiasis and DM type 2. Method. This research was a case controlstudy which took place in Dermatovenereology Outpatient Clinic RSUD dr.Soedarso from June until November 2013. The minimum sample for thisresearch was 126 people and divided into two groups. The case groupconsisted of 63 people and the control group consisted of 63 people. Thesubjects were selected by using consecutive sampling and analyzed bychi-square test. Result. There was an association between intertriginouscandidiasis with DM type 2 (p= 0,01). Odds Ratio (OR) value of thisresearch was 2,621 (IK 95% : 1,246 5,516). Conclusion. Intertriginouscandidiasis is associated with DM type 2 and people with DM type 2 havea possibility of 2,621 times higher risk of acquiring intertriginouscandidiasis than people without diabetes mellitus

Pointing control for the SPIDER balloon-borne telescope

We present the technology and control methods developed for the pointing system of the SPIDER experiment. SPIDER is a balloon-borne polarimeter designed to detect the imprint of primordial gravitational waves in the polarization of the Cosmic Microwave Background radiation. We describe the two main components of the telescope's azimuth drive: the reaction wheel and the motorized pivot. A 13 kHz PI control loop runs on a digital signal processor, with feedback from fibre optic rate gyroscopes. This system can control azimuthal speed with < 0.02 deg/s RMS error. To control elevation, SPIDER uses stepper-motor-driven linear actuators to rotate the cryostat, which houses the optical instruments, relative to the outer frame. With the velocity in each axis controlled in this way, higher-level control loops on the onboard flight computers can implement the pointing and scanning observation modes required for the experiment. We have accomplished the non-trivial task of scanning a 5000 lb payload sinusoidally in azimuth at a peak acceleration of 0.8 deg/s$^2$, and a peak speed of 6 deg/s. We can do so while reliably achieving sub-arcminute pointing control accuracy.Comment: 20 pages, 12 figures, Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 914